The Geologist's Scratch Test
Long before engineers had massive hydraulic presses and diamond-tipped microscopes, geologists needed a fast, reliable way to identify rocks out in the field.
In 1812, German mineralogist Friedrich Mohs created the Mohs Scale of Hardness. Instead of complex math, it relies on one brutally simple rule: A harder material will always visibly scratch a softer material.
The 1-to-10 Scale
Mohs selected 10 standard minerals and ranked them from softest (1) to hardest (10).
- Talc: So soft you can scratch it away with your fingernail.
- Gypsum
- Calcite: A copper penny can scratch this.
- Fluorite
- Apatite: A standard glass window sits right around here.
- Orthoclase: A hardened steel nail can scratch this.
- Quartz: Hard enough to easily scratch glass.
- Topaz
- Corundum (Sapphire/Ruby): Incredibly hard.
- Diamond: The absolute hardest. It can scratch every other mineral on the list, but nothing can scratch it.
This simulator allows you to select two minerals to instantly predict the outcome of a physical scratch test in the field.
Where:
Mohs=
Relative Hardness Value (1-10)